A. Field of the Invention
The invention relates to multi-layer card-shaped data carriers, in particular card-shaped data carriers which are individualized with a laser scriber. The invention also relates to a method for incorporating a hidden marking into such a data carrier.
B. Related Art
Identity cards, such as for example credit cards or personal identity cards for a long time have been personalized by means of laser engraving and, upon doing so, provided for example with a passport photograph or other personal data. For personalizing an identity card by laser engraving as a rule the optical properties of the substrate material of the card are irreversibly changed, in particular blackened, through suitable guiding of a laser beam in the shape of a desired marking.
From the document DE 40 33 300 A1 it is known to provide a card-shaped data carrier, using a laser scriber, with an individualizing information item that is visually not visible, but that can be read out by machine using an infrared checking device. The individualizing information for this purpose is written through a camouflage layer that is black in the visible spectral range, but pervious to infrared radiation into a layer disposed underneath. The reading of the hidden information here in principle requires a corresponding reading device, since the black camouflage layer is pervious only to infrared radiation.
Proceeding from this it is the object of the invention to specify a data carrier of the type mentioned at the outset, that avoids the disadvantages of the prior art and that in particular makes possible a check of a hidden laser marking without using an additional reading device.